The effective management and maintenance of large dairy herds and the production of diary products has been a major agricultural accomplishment. One of the problems in maintaining large herds is the health of the individual animals. One health problem in individual animals of dairy herds that causes significant economic problems relates to mastitis. Often during milking the animals skin is irritated by automatic milking machines. This irritation, characterized by redness and occasionally areas of broken skin, can be the site of a microbial attack causing mastitis. Animals that contract mastitis must be removed from service resulting in the loss of the dairy output. As a result, a significant amount of attention has been focused on preventing the development of mastitis or treating mastitis in dairy herds.
The dairy farmer is faced with two different types of mastitis infections. Contagious mastitis is spread during the milking process through contact between the animal and dairy equipment that may carry a source of a mastitis pathogen. Contagious mastitis is most easily controlled using germicidal post milking teat dips. Such germicidal dips then kill bacteria that are introduced onto the surface of the animal from the milking machines. The second type of mastitis, environmental mastitis, is caused by contamination of the animal surface by materials from the barn yard environment, fields, barn interior, etc. Such pathogens include E. coli, Streptococcus uberis, klebsiella and others. Such contamination occurs as the animal moves through its environment. Environmental mastitis is best treated with a barrier film that protects sensitive tissues from contamination.
In the treatment and prevention of mastitis, the use of protective coatings, formed from aqueous coating systems, on the animals has been an option for many years. One class of the proposed coating materials are simply film barriers formed on the skin surface to prevent contact between vulnerable tissues and the environment. Another class of coating compositions are actively antimicrobial and prevent the incidence of infection in the animal through the presence of an active biocide in the coating. Barrier-type materials simply prevent direct contact between the skin and contagious materials. Barrier-type materials rarely contain antimicrobial materials. The combination of effective germicidal materials with a film forming or a barrier dip formulation would provide the potential for controlling both contagious and environmental mastitis infections.
Among the materials used in barrier-type or film-type teat dips are solubilized liquids, polyvinylpyrrolidone and other vinyl polymers, protein hydrozylate, natural and synthetic gums, water, ethanol, methanol, isopropanol, soluble polymers, unsaturated fatty oils, cellulose derivatives, acrylic polymer lattices, etc. The latex forms a flexible film on the skin which film can be peeled off after moistening the area. However, removal of the film by peeling can be inconvenient and troublesome and can leave small portions of the film on the animal resulting in potential milk contamination. Further, many antimicrobial materials are incompatible with a variety of polymeric or film forming materials. As a result, some of the most effective and otherwise desirable film formers must be formulated without antimicrobials and must rely entirely on barrier effects to prevent mastitis.
In the typical operations of a dairy herd, the herd is brought into a milking station, the udder is washed to remove the barrier film. Any delay in removal of the film can substantially reduce productivity and substantially increase time required to deal with a large herd. Further difficulty in removing the film can cause abrasion or bruising to the animal which can promote mastitis. Preferably, the films are easily removed, in less than 15 minutes, preferably in less than 10 minutes, and most preferably in less than 5 minutes, using water or mild cleaning solutions. While cleaning can be increased using warm solutions, preferably the mastitis barrier films are removed with cold water that is available in most milking operations. In our experimentation with antimicrobial film forming materials we have found that while a variety of materials can form antimicrobial flexible films on animals, the films can be resistant to easy, quick removal. Further, obtaining a stable aqueous film forming antimicrobial barrier teat dip composition that is easily removable provides an additional formulating challenge. The barrier qualities in the teat dip promote the formation of a resilient flexible coating on the skin and often forms a button or plug on the animal in a location such that the material can flow and form a drip on the teat tip before hardening into a button or plug. This hardened material can often pose the most significant problems in removal of the material prior to milking. In summary, combining a barrier coating, ease of removability with a compatible antimicrobial film system is a significant formulating challenge.
The following references are considered to be representative of the state of this art. Typical disclosures of disinfectant after-milking teat dips (aimed at destroying any pathogens remaining on the teats after milking) can be found in British Patent 1 144 637 (Kelco Chemicals, Ltd.), published on Mar. 5, 1969; Meave et al., J. Dairy Science, 52:6696 (1969); Dodd et al., "Mastitis Control", Biennial Reviews (1970) University of Redding, England, National Institute of Research of Dairying, pp. 21-57; Lentsch, U.S. Pat. No. 4,258,056; Lentsch et al., U.S. Pat. No. 4,376,787; Yang, U. S. Pat. No. 4,446,153; Marhevka, U.S. Pat. No. 5,017,369; Cantor et al., U.S. Pat. No. 3,728,449; Pankey, "Postmilking Teat Antisepsis", Symposium on Bovine Mastitis, Veterinary Clinics of North America: Large Animal Practice, Vol. 6, No. 2, July 1984; Pankey et al., "Efficacy Evaluation of Two New Teat Dip Formulations Under Experimental Challenge", Journal Dairy Science, 68:462-465 (1985), Philpot et al., "Hygiene in the Prevention of Udder Infections. V. Efficacy of Teat Dips Under Experimental Exposure to Mastitis Pathogens, Journal Dairy Science, 61:956-963 (1978), Bennett, "Teat Dip as a Component of Coliform Mastitis Control, Dairy and Food Sanitation, Vol. 2, No. 3, pp. 110-114 (March 1982), Eberhart et al, "Germicidal Teat Dip in a Herd with Low Prevalence of Streptococcus agalactiae and Staphylococcus aureus mastitis", Journal Dairy Science, 66:1390-1395 (1983).
Typical disclosures of protective or barrier-type teat dips can be found in Acres et al., U.S. Pat. No. 3,066,071, Krause, U.S. Pat. No. 3,222,252, Philpot et al., Journal Dairy Science, 58:205-216, Coughman et al., U.S. Pat. No. 3,993,777, Pugliese, U.S. Pat. No. 4,049,830, Silver et al., U. S. Pat. No. 4,199,564, Dybas et al., U.S. Pat. No. 4,311,709 and Andrews et al., U.S. Pat. No. 4,113,854. Still also for examples of such materials, see Farnsworth, Journal of American Verterinary Medical Association, 177:441 (1980) and Farnsworth et al., The Bovine Practitioner, No. 16, pp. 28-29 (1981). Still further, please review Canadian Patent No. 1,065,254 and European Published Application No. 25,640 (Mar. 25, 1981). A substantial need exists for an antimicrobial and barrier teat dip that can be easily and rapidly removed during milking operations.